In Wampler U.S. Pat. No. 5,840,070, a continuous flow pump of rotary design is disclosed, suitable for implantation in humans, for use as a chronic ventricular assist device. The disclosed device uses passive, magnetic radial bearings to maintain an impeller and its support shaft for rotation about an axis, thus eliminating the necessity for a drive shaft seal.
In the FIGS. 11-14 embodiment of Wampler U.S. Pat. No. 5,840,070, the disclosure of which is incorporated herein, the implantable heart pump utilizes two stators, each on opposite sides of the impeller and each having a number of stator coils and pole pieces. Thus the driving mechanism involves electromagnetic coupling between the permanent magnets in the impeller and the driving coils in the stators. It has been found desirable to provide a structural member between the impeller and stators to provide structural support and hermetical sealing. It is desirable for this structural member to be biocompatible, non-thrombogenic and corrosion resistant. There have been considerations of forming these structural members of metal, such as titanium or titanium alloy, or cobalt-chromium-nickel alloy. However, it has been found that the time varying magnetic field in the structure arising from the rotating magnets induces eddy currents in the metal structure, causing energy loss. In addition, such eddy current loss also produces heat dissipation, which may result in blood damage, thrombosis and thromboembolism.
It is, therefore, an object of the present invention to provide a rotary blood pump in which eddy currents such as those induced in a metal structure, are alleviated.
Another object of the present invention is to provide a rotary blood pump having an electromagnetically coupled driving mechanism with structural support and hermetical sealing between the impeller and the stator.
A still further object of the present invention is to use ceramic components in an electromagnetically driven blood pump to improve energy efficiency and biocompatibility.
An additional object of the present invention is to provide a novel blood pump which is sufficiently compact to be implantable in the human body and which uses ceramic components to provide strategic advantages.
A further object of the present invention is to provide a novel rotary blood pump that is small, light, simple in construction, and relatively easy to manufacture.
Other objects and advantages of the present invention will become apparent as the description proceeds.